Cut extrudate dispersal hood

ABSTRACT

A product-spreading hood assembly ( 10 ) for use with a die unit ( 128 ) includes a deflector ( 14 ) having wall structure defining a product inlet opening ( 90 ) and a product outlet opening ( 92 ); the deflector ( 14 ) is preferably generally frustoconical in shape and is supported by a housing ( 12 ). An optional air delivery assembly ( 16 ) allows air currents to be directed from the area of the inlet ( 90 ) towards outlet ( 92 ) to facilitate separation of discrete products. Advantageously, the air currents are delivered in a circumferential fashion about the die unit ( 128 ). Use of the hood assembly ( 10 ) serves to separate high moisture or “sticky” extrudates, thereby preventing agglomeration thereof.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of identically titled application Ser.No. 13/626,683, filed Sep. 25, 2012, is now issued as U.S. Pat No.9,221,627, which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is broadly concerned with a product-spreading hoodassembly operable for use with an outlet die unit in order to separatediscrete products issuing from the die to prevent agglomeration of theproducts. More particularly, the invention is concerned with suchapparatus, and corresponding methods, wherein a substantiallyfrustoconical deflector is disposed about the die unit to deliver theextrudate to a downstream dryer or other processing device in aseparated condition. The invention is particularly useful in theproduction of high moisture or otherwise “sticky” extrudates normallyhaving a tendency to agglomerate.

2. Description of the Prior Art

Extrusion cooking systems have long been used for the preparation ofhuman foods and animal feed products. Broadly speaking, such extrusionsystems include an elongated extruder barrel with one or more elongated,axially rotatable, helically flighted extruder screws within the barrel,together with a downstream restricted orifice extrusion die. In typicalprocessing, the feed ingredients are fed into and through the extruderbarrel where they are subjected to increasing levels of heat, pressureand shear in order to at least partially cook the ingredients and forman extrudate. This extrudate may be cut or otherwise subdivided at ordownstream of the die. Thereafter, the subdivided extrudate is oftensubjected to post-extrusion treatments such as surface application offats and drying.

For many types of conventional extrudates, these extrusion systemsoperate smoothly. However, in certain cases, the food or feed formulashave a tendency to produce very sticky products. In such instances, theextrudates may tend to agglomerate adjacent the die or as the extrudatesfall onto a conveyor or other take-away equipment. For example, the highmoisture products described in co-pending application Ser. No.13/626,644 now is abandoned entitled “Production of Engineered Feed orFood Ingredients by Extrusion,” may tend to excessively agglomerate.

There is accordingly a need in the art for improved apparatus associatedwith a die unit in order to maintain the cut extrudate issuing from thedie unit in a separated condition until such time as the extrudates aresufficiently dried or otherwise processed to over come the tendency toagglomerate.

SUMMARY OF THE INVENTION

The problems outlined above are largely, if not entirely, ameliorated byprovision of a specialized product-spreading hood assembly operable tobe placed adjacent an outlet die unit in order to separate discreteproducts issuing from the die unit. The hood assembly comprises adeflector having wall structure defining a product inlet opening and aproduct outlet opening, with a product-receiving area between the inletand outlet openings. Preferably, the deflector wall structure isgenerally frustoconical in shape with a relatively small product inletopening located in generally circumscribing relationship about the dieunit, and a relatively large product outlet opening spaced from theinlet opening. In addition, a housing disposed about and supporting thedeflector and extending along the length of the deflector and beyond theproduct outlet opening to present a product confinement zone, the zonehaving an open bottom so that products from the outlet opening willgravitate from the housing in a substantially separated condition.

In certain instances, operation of the hood assembly is facilitated bymeans of an air delivery assembly operable to direct air currents from apoint proximal to the product inlet opening and into theproduct-receiving area in a direction towards the outlet opening, withthe air currents operable to substantially maintain the discreteproducts in a separated condition as the products pass through theoutlet opening and into the area. Preferably, the air delivery assemblycomprises a plenum extending at least partially about the portion of thedeflector wall structure defining the product inlet opening, with anairway communicating the plenum so that the air currents are directedinto the plenum and pass through the airway into the product-receivingarea.

An external housing is provided to support the deflector, with thehousing extending along the length of the deflector and beyond to definean open-bottom product confinement zone downstream of the outlet end ofthe deflector.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a preferred product delivery hoodassembly in accordance with the invention;

FIG. 2 is a side elevational view of the hood assembly;

FIG. 3 is a perspective view of the hood assembly, viewing the rear endthereof opposite that illustrated in FIG. 1;

FIG. 4 is a front perspective view similar to that of FIG. 1, butillustrating the hood in its opened position permitting access to theextruder die and knife assembly;

FIG. 5 is a side vertical sectional view of the hood assembly,illustrating the internal components of the assembly;

FIG. 5A is an enlarged, fragmentary view illustrating the airflow pathwithin the hood assembly;

FIG. 6 is a vertical sectional view taken along line 6-6 of FIG. 2; and

FIG. 7 is an enlarged, fragmentary view partially taken along line 6-6of FIG. 2, and further illustrating the details of construction of thehood assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to the drawings, a product-spreading dispersal hood assembly10 is illustrated in FIGS. 1-6, and broadly includes an outer housing 12supporting inner, generally frustoconical deflector 14, and an airdelivery assembly 16. The hood assembly 10 is designed for use withdevices such as extruders or pellet mills, which are equipped with a dieunit to create discrete products; in the exemplary embodiment, the hoodassembly 10 is used in conjunction with a conventional extruder 18. Thepurpose of hood assembly 10 is to maintain the discrete products in aseparated condition for delivery onto a take-away device, such as aninlet belt 20 of a product dryer (see FIG. 2). In this way, the discreteproducts are substantially prevented from agglomerating after extrusionand during downstream drying and/or other processing.

The housing 12 is generally semicircular in overall configuration andincludes a pair of shiftable housing halves 22 and 24. The halves 22, 24are largely mirror images of each other, except for the differencesdescribed below. Thus, each housing half includes a rear end wall 26,28, an elongated arcuate sidewall 30, 32, and a forward end wall 34, 36.The sidewalls 30, 32 have detachable, somewhat U-shaped forward panels38, 40 secured to the sidewalls 30 and 32 by latches 42, 44. Each suchpanel has an inwardly extending wall segment 38 a, 40 a, each having anarcuate inner margin which abuts the adjacent sidewall 30 or 32. Thehalves 22, 24 cooperatively define the complete overall housing 12 whenthe walls are placed in adjacency, as illustrated in FIG. 1. In order toensure proper attachment between the halves 22, 24, the pair ofalignment tabs 46 are provided on the butt edges of the front end walls34, 36, and a fore and aft latches 48 and 49 are provided tointerconnect the halves. As depicted in FIG. 1, the front end walls 34,36 are cooperatively designed to provide a knife drive opening 50, whichis important for purposes to be described, and are also equipped withobservation ports 52, 54. A bracket 56, 58 is secured to the outersurface of each sidewall 30, 32 and supports a spherical mount 60, 62.

The deflector 14 is made up of two largely mirror image,half-frustoconical walls 64, 66, with each wall being secured to andextending along the length of a corresponding housing half 22, 24 sothat, when the halves 22 and 24 are closed together, the walls 64, 66cooperatively define the substantially frustoconical deflector 14. Asillustrated in FIGS. 4 and 5, the wall 64 is welded or otherwise affixedto the inner surface of sidewall 30, and is further supported by meansof tabs 68 secured to rear end wall 26. As such, it will be observedthat a semicircular, generally triangular in cross-section, open-endedairway 70 is defined between the outer surface of wall 64, the innersurface of sidewall 30, and the inner surface of end wall 26. Asemicircular air outlet 72 is in communication with airway 70 and isdefined between the inboard margin 74 of wall 64 and a semicircularcollar 76, the latter being secured to and extending forwardly from rearend wall 26.

The frustoconical wall 66 is likewise secured to the inner surface ofhousing sidewall 32, thereby also defining a semicircular, generallytriangular in cross-section airway 78 between the outer surface of wall66, the inner surface of sidewall 32, and the inner surface of end wall28. A lower tab 80 provides further support for the wall 66. However, atthe upper end of the airway 78, a somewhat triangular panel 82 isprovided which closes the upper end of airway 78. A semicircular airoutlet 84 in communication with airway 78 is defined between the innermargin 86 of wall 66 and a semicircular collar 88 affixed to end wall28.

It will be appreciated that when the halves 22, 24 are closed againsteach other and latched together, the abutting walls 64, 66 define thesubstantially frustoconical deflector 14 having a relatively smallproduct inlet opening 90 defined by the abutting collars 76 and 88; arelatively large deflector product outlet opening 92 in spaced andopposed relationship to the opening 90 and defined by the outer margins94, 96 of the walls 64, 66; an essentially full-circle airway 98 definedby the aligned airways 70 and 78; a circular air outlet 100 defined bythe now-aligned outlets 72 and 84 in communication with airway 98; andthat the sidewalls 64 and 66 forward of the outer margins 94, 96, thefront walls 34, 36, and the panels 38, 40 cooperatively provide a anelongated, laterally extending, open-bottom product confinement zone102.

The air delivery assembly 16 is designed to supply airway 98 withpressurized air, and to direct such air through the outlet 100 in adirection towards the outlet opening 92 of deflector 14.

To this end, an air inlet pipe 104 is secured to sidewall 32 and isdesigned to receive an air conduit (not shown), supplying pressurizedair for passage through airway 98 and outlet 100.

The extruder 18 in the illustrated embodiment has an elongated, tubular,multiple-head barrel including a terminal head 106, with a pair ofelongated, helically flighted, axially rotatable extrusion screws 108within the barrel. The outlet end of head 106 is equipped with atransition 110 which is secured to the inlet 112 of a back pressurevalve assembly 114. The assembly 114 is itself conventional, and isdesigned to provide a selective degree of restriction to flow ofmaterial from the extruder barrel. The valve assembly is illustrated anddescribed in detail in U.S. Pat. No. 6,773,739, wherein the portionsthereof directed to the back pressure valve assembly 114 areincorporated by reference herein in their entireties. The outlet 116 ofthe assembly 114 is equipped with a transition 118, the lattersupporting a circular spacer 120. A die plate support 121 is mounted onspacer 120, and in turn supports a restricted orifice die plate 122having a plurality of die openings therethrough.

A multiple-blade rotary cutoff knife 124 is positioned against the outerface of die plate 122, and is secured to a knife shaft 126. The shaft126 extends through the shaft opening 50 and is coupled with aconventional motor drive (not shown). It will thus be appreciated thatthe die plate 122 and knife 124 provide a die unit 128, which, with theoverall extruder 18, provides discrete cut extrudate products.

In order to further support the housing halves 22, 24 during swingingmovement thereof, a pair of hinged support arms 130, 132 are operativelyconnected between the back pressure valve assembly 114 and therespective spherical mounts 60, 62. In this manner, the halves 22, 24may be easily swung between the closed position of FIG. 1 and the open,access position of FIG. 4.

In the operation of hood assembly 10, the use of air delivery assembly16 is optional, i.e., with some products, it is unnecessary to provideair currents surrounding the die unit 128.

In other instances, the air delivery assembly 16 facilitates separationof the cut extrudate. When used, the assembly 16 may be operated at avelocity of up to about 6,000 cubic feet/minute (cfm), more usually fromabout 2,000-4,000 cfm, and most typically about 3,000 cfm. The air maybe ambient temperature air or heated to a temperature of up to about 80°C. Ambient air is preferred for reasons of cost, and also becauseambient air helps to “set” the surface of the extrudates to reducestickiness. In any case, use of the assembly 16 also helps deflect theextrudates so that they strike the deflector 14 at a lower angle,thereby reducing the probability of agglomeration on the side of thedeflector.

While the invention has been described in the context of the twin screwextruder 18, the invention is not so limited. That is, a single screwextruder could also be used or, for that matter, any other processingdevice, such as a pellet mill which will generate cut extrudateproducts. Moreover, while the support arms 130, 132 have been shown asmounted on the back pressure valve 114 assembly, this is a matter ofconvenience only, and such support arms, where used, may be supported onany other convenient portion of the overall apparatus.

We claim:
 1. A method of spreading a plurality of discrete productsissuing from a die unit having a generally horizontal axis, comprisingthe steps of: directing said discrete products into a hollow, open-endeddeflector comprising a generally frustoconical wall section presenting asubstantially horizontal central longitudinal axis, a product inletopening having a first cross-sectional area, a spaced product outletopening having a second cross-sectional area greater than said firstcross-sectional area, said product outlet opening presenting an outermargin, and a product-receiving area located between said product inletand outlet openings; causing said discrete products to impinge upon saidfrustoconical wall section to pass out of said product outlet openinginto and through a product delivery opening, said product deliveryopening located outboard of said product outlet opening's outer margin,so to gravitate away said discrete products from the open endeddeflector in a direction transverse to said horizontal centrallongitudinal axis during passage of said discrete products into andthrough said product delivery opening; and using an air deliveryassembly to direct air currents into said product-receiving area from apoint proximal to said inlet opening towards said outlet opening, saidair currents operable to substantially maintain said discrete productsin a separated condition as the products pass through said outletopening.
 2. The method of claim 1, said air delivery assembly comprisinga plenum extending at least partially about said product inlet opening.3. The method of claim 2, there being an airway substantiallycircumscribing said product inlet opening.
 4. The method of claim 1,including the steps of extruding product from an extruder through saiddie unit, and cutting product issuing from the die unit to give saiddiscrete products.
 5. A method of spreading a plurality of discreteproducts issuing from a die unit having a generally horizontal axis,comprising the steps of: directing said discrete products into a hollow,open-ended deflector comprising a generally frustoconical wall sectionpresenting a substantially horizontal central longitudinal axis, aproduct inlet opening having a first cross-sectional area, a spacedproduct outlet opening having a second cross-sectional area greater thansaid first cross-sectional area, said product outlet opening presentingan outer margin, and a product-receiving area located between saidproduct inlet and outlet openings; and causing said discrete products toimpinge upon said frustoconical wall section to pass out of said productoutlet opening into and through a product delivery opening, said productdelivery opening located outboard of said product outlet opening's outermargin, to gravitate away said discrete products from said open-endeddeflector in a direction transverse to said horizontal centrallongitudinal axis during passage of said discrete products into andthrough said product delivery opening.
 6. The method of claim 5,including the steps of using an air delivery assembly to direct aircurrents into said product-receiving area from a point proximal to saidinlet opening towards said outlet opening.
 7. The method of claim 6,including the step of directing said air currents into said deflectorfrom a point proximal to said product inlet opening in a directiontoward said product outlet opening.
 8. The method of claim 5, includingthe step of forming said discrete products by cutting extrudate issuingfrom the die unit.